I've never circulated during the initial infusion mash, I just stir every 15 minutes or so. I'm sure recirculation is intended to give you an extra few points in your efficiency but to me it's more trouble than it's worth. Same with fly-sparging vs batch-sparging. With older undermodified malts it was probably needed, but I haven't seen the need with todays grain. Maybe with your next batch you could try holding temp during the initial mash and just stir every once in a while.

Three mashes - 2 lbs of 2-row each mashed with 2.5 quarts of water at 152 for 60 minutes

One batch crushed at .030", on crushed at .033" and one crushed at .035".

Mash em all and then take readings.

I realize that:
#1 This will only be mash efficiency and not brewhouse efficiency
#2 As I will be doing this on the stovetop with smaller pots it will not be representative of what my system will get - concerning issues of if the crush is too fine there being a stuck sparge.

I will probably then sparge each of them, combine and maybe make a 3 gallon batch out of it - I mean why waste the mash? :P

Please share your results after you finish the experiment. I've noticed pretty significant differences in efficiency related solely to the crush. But there's a trade-off in in lautering flow. When I crush fine, I'll get great efficiency but it'll drain painfully slow if I don't toss in some rice hulls. A coarser crush makes for easy lautering/sparging but less efficiency--it's all about finding that middle ground. This is one factor that the mini-experiment won't give you good insight into since it won't be done on your brew equipment and in the quantities you'd typically brew with. Still, I think your test is worthwhile, and you'll either have a mini-batch to show for it or a lot of wort for future starters.

Please share your results after you finish the experiment. I've noticed pretty significant differences in efficiency related solely to the crush. But there's a trade-off in in lautering flow. When I crush fine, I'll get great efficiency but it'll drain painfully slow if I don't toss in some rice hulls. A coarser crush makes for easy lautering/sparging but less efficiency--it's all about finding that middle ground. This is one factor that the mini-experiment won't give you good insight into since it won't be done on your brew equipment and in the quantities you'd typically brew with. Still, I think your test is worthwhile, and you'll either have a mini-batch to show for it or a lot of wort for future starters.

Will do. I plan on doing this at some point this weekend.

I just picked up a mini-feeler gauge to calibrate my mill yesterday ($3 from AutoZone). I went to set it and oh man, I must've messed with it before, because that gap was nowhere near .035" - much wider :P

One thing you can do to see if you are extracting all the sugars from the grain during mashing is look at this chart from braukaiser.com.
Once you are done mashing recirculate just to get the liquid from below the false bottom mixed throughout (recirculate maybe ~10secs) then take a gravity reading of the wort.
Look at the chart for the mash thickness you used and see if the gravity matches. If not, you know your weren't fully converted and something is wrong on that end (crush, temperature, pH, time, diastatic power, water/grist ratio, mash schedule)

On the other hand, it could be you're losing a lot of sugars when lautering. Follow the procedures under "Testing the lauter efficiency (fly and batch sparging)" to get an idea if this part of your process is where you are losing your sugars.http://braukaiser.com/wiki/index.php...use_Efficiency

I did these tests the last time I brewed and and found I was having trouble with lautering.

Well, here's a doozy, so I did that experiment dialing in my mill settings and just today did an actual batch on my actual equipment. 3 15 gallon pots, mash tun has a MoreBeer false bottom with about 3 gallons of "deadspace" under it. So my mill was set to .030" and I did malt conditioning as well.

I did this Old Foghorn clone that calls for 21 lbs of 2 row, and 1 lb of 80L Crystal. I mashed with 6.875 gallons (1.25 qt/lb) got about 5 gallons from first runnings and then sparged with 180 degree water for the other 2.5 gallons. Pre boil came out to 18 brix (I took a sample and waited for it to get down to 68 degrees) which according to this should be 1.074. Post boil came out to be 1.075 with the hydrometer. Admittedly when I added the strike water to the mash tun, by the time I mixed all of the grain in the temp had dropped to the low 140s, so I turned the burner on under the mash tun until I got it sitting around 158 (which I figured that it would drop during the next 60 minutes but it really didn't). Mashed for 60 minutes once it was at 158 then sparged with 180, stirred like crazy then recirced til it was clear and ran off the remaining 2.5 gallons to the BK. Could the high mash temp have had an effect on my (ridiculously low) efficiency? Is it possible that for some reason I am not getting full conversion during my mash process? The wort tasted sweet as all, but should I be testing it with strips / iodine?

Or could it be that I am trying to do 5 gallon batches in 15 gallon pots?

I am reallly at a loss here - Unless I have Brewtarget configured wrong it is telling me that I just got 49% efficiency.